The effects of temperature, salinity, and the carbonate system on Mg/Ca in Globigerinoides ruber (white) : a global sediment trap calibration
View/ Open
Date
15/01/2018Author
Keywords
Metadata
Show full item recordAltmetrics Handle Statistics
Altmetrics DOI Statistics
Abstract
The Mg/Ca of planktic foraminifera Globigerinoides ruber (white) is a widely applied proxy for tropical and sub-tropical sea-surface temperature. The accuracy with which temperature can be reconstructed depends on how accurately relationships between Mg/Ca and temperature and the multiple secondary controls on Mg/Ca are known; however, these relationships remain poorly quantified under oceanic conditions. Here, we present new calibrations based on 440 sediment trap/plankton tow samples from the Atlantic, Pacific and Indian Oceans, including 130 new samples from the Bay of Bengal/Arabian Sea and the tropical Atlantic Ocean. Our results indicate temperature, salinity and the carbonate system all significantly influence Mg/Ca in G. ruber (white). We propose two calibration models: The first model assumes pH is the controlling carbonate system parameter. In this model, Mg/Ca has a temperature sensitivity of 6.0±0.8%/°C (2σ), a salinity sensitivity of 3.3±2.2%/PSU and a pH sensitivity of −8.3±7.7%/0.1 pH units; The second model assumes carbonate ion concentration ([CO32−]) is the controlling carbonate system parameter. In this model, Mg/Ca has a temperature sensitivity of 6.7±0.8%/°C, a salinity sensitivity of 5.0±3.0%/PSU and a [CO32−] sensitivity of −0.24±0.11%/μmol kg−1. In both models, the temperature sensitivity is significantly lower than the widely-applied sensitivity of 9.0±0.6%/°C. Application of our new calibrations to down-core data from the Last Glacial Maximum, considering whole ocean changes in salinity and carbonate chemistry, indicate a cooling of 2.4±1.6°C in the tropical oceans if pH is the controlling parameter and 1.5±1.4°C if [CO32−] is the controlling parameter.
Citation
Gray , W R , Weldeab , S , Lea , D W , Rosenthal , Y , Gruber , N , Donner , B & Fischer , G 2018 , ' The effects of temperature, salinity, and the carbonate system on Mg/Ca in Globigerinoides ruber (white) : a global sediment trap calibration ' , Earth and Planetary Science Letters , vol. 482 , pp. 607-620 . https://doi.org/10.1016/j.epsl.2017.11.026
Publication
Earth and Planetary Science Letters
Status
Peer reviewed
ISSN
0012-821XType
Journal article
Rights
© 2017 Elsevier B.V. This work has been made available online in accordance with the publisher’s policies. This is the author created, accepted version manuscript following peer review and may differ slightly from the final published version. The final published version of this work is available at https://doi.org/10.1016/j.epsl.2017.11.026
Description
This research was funded by NSF grant NSF-OCE 1260696 awarded to S. Weldeab and D.W. Lea.Collections
Items in the St Andrews Research Repository are protected by copyright, with all rights reserved, unless otherwise indicated.